The present invention relates generally to a draft control system of the type normally used on agricultural tractors and more specifically relates to the support for a load sensing bar which forms part of the draft control system.
Many draft control systems currently in use today utilize a bending bar to sense the draft load in the manner disclosed in U.S. Pat. No. 2,940,530. The bar normally extends through the transmission casing of a tractor and has draft links attached to its opposite ends. When load is applied to the draft links, the bar is caused to bow about its supports in the opposite sides of the casing and the movement of the bar, as it bows, is utilized to operate a valve which controls the flow of fluid to and from a hydraulic cylinder which, through appropriate mechanical linkage, causes the draft links to be raised and lowered. Devices of this type are utilized to regulate the working depth of the implement attached to the draft links in order to maintain a relatively constant draft load on the tractor.
As shown in U.S. Pat. No. 2,940,530, it has been known to provide a stop member to limit the bending of the bar to a predetermined amount which lies within the normal working range of the load control system. Such a stop prevents damage to the shaft in the event it is subjected to an excessively high impulse load, such as may occur if a plow share encounters a rock or other relatively immovable object. As shown in U.S. Pat. No. 4,315,548, it has been known to support the load control shaft in spherical bearings which distributes the load on the shaft over a relatively large area, thus avoiding a point or line contact which could cause an overstress and failure of the shaft. This area of contact also reduces abrasive wear on the shaft as it slides in its support due to the bending action. Also as shown in U.S. Pat. No. 4,315,548, it has been known to support the spherical bearing in a mount or bracket which is separate from, but securely attached to, the tractor transmission casing. This not only eliminates the necessity to machine the casing in the area of the bar support, but makes the support easily removable for repair or replacement.